(1) Field of the Invention
The invention relates to a display device, and more particularly to a liquid crystal display including a touch panel.
(2) Description of the Related Art
In a liquid crystal display device, a TFT substrate where pixel electrodes and thin film transistors (TFT) are formed in a matrix shape and an opposite substrate facing the TFT substrate are arranged and liquid crystals are interposed between the TFT substrate and the opposite substrate. Then, an image is formed by controlling a light transmittance of liquid crystal molecules per each pixel.
In a small and medium sized liquid crystal display device, an input method with a touch panel is widely used. A touch panel is attached to the upper surface of an upper polarizing plate in a liquid crystal display panel with a bonding agent. In this attachment process, the attachment work is often performed in a decompressed atmosphere in order to avoid air bubbles entering into the bonding agent.
When the liquid crystal display device is moved from the air to a decompressed atmosphere, balance of pressure may collapse and a hermetically sealed air may expand in an enclosed space, which causes a deformation in the liquid crystal display device. Japanese Patent Laid-Open Publication No. 2009-80289 discloses the structure in which when a touch panel is attached to a liquid crystal display panel in the decompressed atmosphere, an air hole is formed in the touch panel in order to inhibit deformation from occurring in the touch panel because of the expansion of the air inside the touch panel.